Time-out

ABSTRACT

APPARATUS FOR SHARING INPUT/OUT PUT DEVICES AMONG A GROUP OF CHANNELS SUCH THAT AUTOMATIC PATH FINDING AND DYNAMIC SHARING WITHIN THE CHANNEL GROUP IS ACHIEVED. THE SYSTEM PROVIDES MORE EFFICIENT CHANNEL UTILIZATION WITH FEWER SYSTEM INTERRUPTIONS. ANY ONE CHANNEL OF A GROUP OF SIMILAR CHANNELS, EACH OF WHICH HAS ACCESS TO UNIT CONTROL WORDS FOR A SET OF ATTACHED DEVICES, PERFORMS I/O OPERATIONS WITHOUT PROGRAM SELECTION OF A SPECIFIC CHANNEL. WITH THIS TYPE OF AN INPUT/OUTPUT SYSTEM, A START I/O INSTRUCTION SPECIFIES A CHANNEL GROUP AND A PARTICULAR DEVICE SO THAT ANY CHANNEL IN THE GROUP THAT IS NOT BUSY AT THE TIME THE INSTRUCTION IS ISSUED WILL EXECUTE THE INSTRUCTION. ALSO DISCLOSED IS A UNIT CONTROL WORD STRUCTURE THAT ALLOWS THE NUMBER OF UNIT CONTROL WORDS ASSIGNED TO A GICEN I/O INTERFACE TO BE DETERMINED INDEPENDENTLY OF THE NUMBER OF UCW&#39;&#39;S ASSIGNED TO THE OTHER INTERFACES OF THE SYSTEM. IT ALSO ALLOWS SHARED SUB-CHANNEL ASSIGNMENT TO BE DETERMINED INDEPENDENTLY OF THE DEVICE ADDRESS STRUCTURE. THE UCW STRUCTURE ALSO ALLOWS SHARING OF UCW SETS AMONG CHANNELS TO ACCOMMODATE INTERFACE SHARING.

DEFENSIVE PUBLICATION UNITED STATES PATENT AND TRADEMARK OFFICEPublished at the request of the applicant or owner in accordance withthe Notice of Dec. 16,1969, 869 0.G. 687. The abstracts of DefensivePublication applications are identified by distinctly numbered seriesand are arranged chronologically. The heading of each abstract indicatesthe number of pages of specification, including claims and sheets ofdrawings contained in the application as originally filed. The files ofthese applications are available to the public for inspection andreproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to themerits of alleged invention. The Patent and Trademark Oflice makes noassertion as to the novelty of the disclosed subject matter.

PUBLISHED NOVEMBER 4, 1975 T940,021 INPUT/OUTPUT SYSTEM WITH CHANNELGRBUPS AND DYNAMIC SHARING 0F 1/0 DEVICES Paul J. Brown, Poughlrecpsie,and Roger L. Carmier,

Pleasant Vniicy, fifitl, as gaiors to international Business Machines(Torporntion. Armenia. NJ. Continuation of application Ser. No. 320il43, Jan. 2, 1973. This application June 24, 1974, Ser. No. 482,539Int. Cl. Gear 3/00, 15/20 [1.5. Cl. 340-4725 6 Sheets Drawing. 24 PagesSpecification CPU o1 INK SWR GE W SillliEU lICI Sl'lHlBE Apparatus forsharing input/output devices among a group of channels such thatautomatic path finding and dynamic sharing within the channel group isachieved. The system provides more efiicient channel utilization withfewer system interruptions.

Any one channel of a group of similar channels, each of which has accessto unit control words for a set of attached devices, performs I/Ooperations without program selection of a specific channel. With thistype of an input/output system, a start I/O instruction specifics achannel group and a particular device so that any channel in the groupthat is not busy at the time the instruction is issued will execute theinstruction.

Also disclosed is a unit control word structure that allows the numberof unit control words assigned to a given I/O interface to be determinedindependently of the number of UCWs assigned to the other interfaces ofthe system. It also allows shared sub-channel assignment to bedetermined independently of the device address structure. The UCWstructure also allows sharing of UCW sets among channels to accommodateinterface sharing.

Nov. 4, 1975 P. J. BROWN et a1. T940,021

INPUT/OUTPUT SYSTEM WITH CHANNEL GROUPS AND DYNAMIC SHARING OF I/ODEVICES Original Filed June 24, 1974 Sheetlof6 F I G 4 CPU L MAINSTORAGE 16 sumo SHARED 2O 18 ucw STORAGE ucw STORAGE CONNECTION HELDCHANNEL CHANNEL 12 GROUP GROUP /14 CHAN CHAN cm cm 0mm CHAN 01 02 0s 0102 0s 24/ i i i SW SW SW HOLD CONNECTJON CU CU CU 28 C/ INTERFACEO 50INTERFACE SWITCH Nov. 4, 1975 P. J. BROWN et a1. INPUT/ OUTPUT SYSTEMWITH CHANNEL GROUPS AND DYNAMIC SHARING OF 110 DEVICES Original FiledJune 24, 1974 FIG.2

Sheet 2 of 6 CHANNEL 1 POINTER: OOOI0 00 CHANNEL 2 POINTER; O0 OOIO 08STORAGE LOCATIONS:

OF OE I000 00 00 II I0 1004 00 00 10 10 I 1008 00 00 11 10 BASE 1 1115111000 00 00 10 10 :IOIO 02 0000000000 OOOOOOOFOOOOOOOEOO O0 1020 02 0a 0000 03 00 00 00 00 00 00 00 00 00 00 00 IOFO 6E I 00111 UA CONTENTSPOINTERS Nov. 4, 1975 P. J. BROWN et a1. T940,021

INPUT/OUTPUT SYSTEM WITH CHANNEL GROUPS AND DYNAMIC SHARING OF I ODEVICES Sheet 3 0f 6 Original Filed June 24, 1974 STORAGE LOCATIONS O OO O O 0 0 0 O 0 FIG.3

IOLZ ARUB QOOuAHDAUnUELFO la i ia i i ii ll iil lnfind l iii ii iil l iiii l ali CHANNEL 1 P0 I NTER 000010 00 STORAGE LOCATIONS 0 0000 0 000 m00 0 0 000 0 OOEO O 0000 0 0000 0000 R F000 E 000 13000 i 0000 0 .LIGFODI 00 0 0500 2 000 L 00 0 EL 0000 N 0000 M 0 00 H 0008 C 0000 0 0 00 m5000 00 0000 ill 0000 00 00000 007.0 8 00 0 00 13 00 0000 0 0000000 00 000 1254 670 9A 00 00 0000000000000 ili ii liiiiiilli ilil il iilil 8 llwc Nov. 4, 1975 Original Filed June 24, 1974 F I G. 5

INITIAL SELECTION SEQUENCE I/O INTERRUPTION ZERO 4-? OF B-RECISTERRETAIN BO-S DECREMENT BCAL. BCAL=T P. J. BROWN et a1. INPUT/ OUTPUTSYSTEM WITH CHANNEL GROUPS AND DYNAMIC SHARING OF I/ O DEVICES I BEGIN II/O INSTRUCTIONS I/O INTERRUPTION & CHANNEL RETRY SEOUENOES USE THREECOUNTDOWN LOOPS I. TIME-OUT I ZETIME-OUT 2 5.SELECTIVE RESET Sheet 4 of6 I I INTERRUPTION ROUTINE I RETRY SET CONDITION CODE TURN ON RESULTSTORED TOR,

TURN OFF SELECT CHAN.

TGR TURN OFF CHANNEL CHANNEL RESPONSE TGR I CHANNEL SELECTION I SET TOZERO, LOGIC (FIG-6) EOP & CHANNEL SELECT SENT, I PRIOR TO HERE- ZERO THEREGISTER 1c SAVED DECREMENT BCAL IN 0 REG 4-? BCAL= 1 242 Nov. 4, 1975P. J. BROWN et a1. T940,021

INPUT/OUTPUT SYSTEM WITH CHANNEL GROUPS AND DYNAMIC SHARING OF I/ ODEVICES Sheet 5 of 6 Original Filed June 24, 1974 A 251mm V A: E1 22:;$0 .2220 2522 :w 55% 3 5E OCBS 228357:

Sm: 223E209.

Nov. 4, 1975 P. J. BROWN et a1. T940,02l

INPUT/OUTPUT SYSTEM WITH CHANNEL GROUPS AND DYNAMIC SHARING OF NODEVICES Original Filed June 24, 1974 Sheet 6 of 6 F I G. 7

START I/O MAJOR OPERATION I CPU INITIATES START I/O INSTRUCTION \252 ICHANNEL ACCEPTS START 1/0 INSTRUCTION SET START I/O MAJOR OPERATIONLATCH 56 UNIT ADDRESS SETUP SEQUENCE TRANSLATE UA ucw ADDRESS UCWSEQUENCE CONTROL FETCH SEQUENCE 264 CONTROL INSPECTION SEQUENCE \2 I UCWSEQUENCE

